Eating fish: being healthy and safe

By Deborah Swackhamer

From eNews July 19, 2007

Fish is an important part of a healthy, balanced diet. High in
heart-healthy omega 3 fatty acids, fish is a low-fat source of
protein and nutrients. Reports about chemical contamination in
water, however, raise questions about how these chemicals may
affect your health. It's a balancing act: to be both healthy and
safe, you should eat fish, but avoid unlimited consumption.

All fish--whether caught locally or purchased in restaurants and
stores--contain some environmental chemical contaminants. Three
types of chemicals are found in Minnesota fish: mercury,
polychlorinated biphenyls (PCBs), and perfluorinated compounds
(PFCs). These chemicals come largely from industrial sources and
man-made products that pollute air and landfills. Over time, they
enter lakes, rivers, or oceans and move up through the food web,
eventually accumulating in fish. Fish that are bigger, older, or
higher in the food web have the most contaminants.

The government regulates the safety of commercially sold fish
and issues advisories about fish consumption. Minnesota was one of
the first states to develop these advisories and has some of the
most rigorous procedures for determining advice it provides. The
Minnesota
Department of Health's Web site includes a fish consumption
advice section, offering resources for anglers and fish
consumers.

Mercury, PCBs, and PFCs have negative effects on human health,
particularly on early development. Because of the impact of these
chemicals on developing fetuses, infants, and young children, fish
consumption guidelines are stricter for women who are pregnant or
might become pregnant, women who are breastfeeding, and children
under the age of 15 than they are for the general population. For
example, women of childbearing age and children should avoid shark,
swordfish, tilefish, and king mackerel because they have high
mercury levels, while the general population should limit
consumption.

At the University of Minnesota, scientists are studying why fish
have higher levels of chemical contamination than other meats, such
as beef or chicken. The length of the food web appears to be
important. While cows and poultry are part of a short food web,
fish are near the end of a longer food web. Because each step in a
food web has an additive effect on chemical build-up, contaminants
can reach significant concentrations in the fish on your dinner
table. Understanding this "bioaccumulation" of chemicals may be the
first step in developing strategies to interrupt or minimize the
process, improving food safety.

When it comes to eating fish:

eat a balanced diet that includes some fish;

choose smaller varieties when eating local fish; and

remove skin and fat to lower the level of PCBs. Mercury cannot
be removed by cooking or cleaning fish.

Deborah Swackhamer is professor of environmental health
sciences in the School of Public Health and interim director of the
Institute on the Environment.